1. Field of the Invention
The present invention relates to a network management apparatus, and in particular to a network management apparatus which manages a network composed of network elements implementing or installing different communication technologies such as an ATM (Asynchronous Transfer Mode), an MPLS (Multi-Protocol Label Switching), and a Diff-Serv (Differentiated Services).
Such a network management apparatus, when a Quality of Service (hereinafter, abbreviated as QoS) is requested in the network, is required to select a network element to be guaranteed with the QoS and to perform a QoS guarantee setting in each selected network element.
2. Description of the Related Art
FIG. 18A shows a general network composed of network elements respectively installing different communication technologies. In this network, edge nodes (network elements) 20—1 and 20—4 are connected through an ATM node 20—2 or a DiffServ node 20—3. Between the edge nodes 20—1 and 20—4, there are following three routes; (1) link 30—1→ATM node 20—2→link 30—3, (2) link 30—1→ATM node 20—2→link 30—4→DiffServ node 20—3→link 30—5, and (3) link 30—2→DiffServ node 20—3→link 30—5.
In the absence of an empty band in the links 30—2 and 30—3, the route (2) (shown by thick lines) through the edge nodes 20—1 and 20—4 connected in cascade is the only route.
FIG. 18B shows a general network example in which the nodes (network elements) 20—1 and 20—2, whose communication technologies such as a QoS guarantee and a flow identifier assignment capability are different from each other, are connected with the link 30—1 and the node 20—3 which is different from the node 20—2 is connected to the node 20—2 with the link 30—2.
Cases 1–4 respectively show that the nodes 20—1 and 20—3 employ an IP-ONU (Optical Network Unit), a DiffServ router, an LSR (Label Switch Router), or a router, and the node 20—2 employs an OLT (Optical Line Terminal), a DiffServ core router, a core LSR, or an ATM switch.
Thus, a general network is composed of network elements which mount thereon various communication technologies.
Hereinafter, the QoS guarantee in such a network will be described.
In a prior art IP network, as in the Internet, the QoS guarantee of the communication could not be performed, so that a best-effort type communication has been performed.
Also, in an IntServ of the IETF (Internet Engineering Task Force), a resource at the time of a communication has been secured by using a signaling technology RSVP (Resource ReSerVation Protocol) for a band guarantee path establishment, so that the QoS has been guaranteed.
Also, in a DiffServ technology of the IETF, the QoS guarantee per DSCP (DiffServ Code Point) has been set in the network element for setting a band guarantee.
However, only the network element which mounts thereon a single QoS guarantee mechanism such as the IntServ or the DiffServ has been able to guarantee the QoS, which limits the QoS guarantee.
Also, in an MPLS of the IETF, a mechanism of autonomously establishing a path has been prescribed so that an edge router assigns an identifier to an IP flow and a core router transfers an IP packet according to the identifier. However, a mechanism of exchanging information on the QoS guarantee setting has not been prescribed.
Also, while the QoS setting is possible in case the path is explicitly established manually or the like, the retrieval of a route and the preparation of QoS guarantee setting contents are required to be performed manually.
In such a prior art network management apparatus, there have been problems that the calculation of a QoS guarantee route and the preparation of the QoS guarantee setting contents can not be automatized, requiring much process time for the QoS control by end to end in the network composed of a plurality of sub-networks whose communication technologies such as a QoS guarantee and a flow identifier assignment capability are different from each other.